Speed bumps are widely used as a device for compelling drivers to decrease their speed, especially in speed restricted areas. The speed bumps are generally deployed along a road at appropriated distances and are generally integrally constructed as a part of the road. Warning signs are usually located along the road to warn a driver of the approaching speed bump. As the driver approaches the speed bump, the driver generally decreases the speed of the car in order to avoid hitting the speed bump at a high speed.
However, the warning signs are not generally effective in slowing down fast drivers and additionally even if the driver slows down to the required speed, the car may still suffer a jolt. Such a jolt may not only be a serious nuisance but may even damage the car. Furthermore, the jolt may even be sufficiently strong so as to cause injury to the car travelers.
Additionally, the driver may not always be aware of the existence of these speed bumps, especially when driving at night which will make the speed bumps even more annoying.
U.S. Pat. No. 5,267,808 to Welford describes a retractable electronically controlled speed bump with a microprocessor controller and a vehicle speed sensor. The controller is operative to extend or retract the speed bump in response to the sensed speed of an oncoming vehicle.
U.S. Pat. No. 4,974,991 to Mandavi describes a speed bump apparatus comprising a transverse bump bar, a pendulum and a mechanical locking mechanism.
U.S. Pat. No. 4,627,763 to Roemer describes a barrier apparatus comprising a pivoting barrier with energy absorbing members and hydraulic motors for raising the barrier thereby preventing unauthorized passage of vehicles.
U.S. Pat. No. 3,748,782 to Reynolds describes a mechanically activated traffic flow controller movable between a raised position and lowered position when a vehicle drives over it. The barrier is raised to an intermediate position when the front wheels of a vehicle pass thereover and is moved to the raised position when the rear wheel move thereover.
U.S. Pat. No. 4,342,525 to Mastronuzzi describes a retractable speed bump comprising moveable wedge shaped members and an upper member which may be moved above street level.
U.S. Pat. No. 4,332,503 to Hurst describes a pivotally mounted ramp for allowing a vehicle to travel substantially freely in one direction while impeding the traffic in the opposite direction.
U.S. Pat. No. 1,878,234 to Goodman describes a retractable speed bump useful in controlling vehicle access at a railroad grade crossing.
U.S. Pat. No. Re. 33,201 to Dickinson describes a retractable barrier activated by a motor driven pump and hydraulics for providing impact absorption to protect the hydraulic system.
There is a need in the art therefore for a speed bump which will be effective for slowing down cars traveling above a given speed limit. Additionally there is a requirement for a speed bump whose slowing down effect is speed dependent and will not be of a nuisance value.